Re: [RFC][PATCH 1.5/2] x86: Add int3_emulate_call() selftest

From: Steven Rostedt
Date: Fri May 03 2019 - 14:47:09 EST

On Fri, 3 May 2019 12:22:47 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> Given that the entry_*.S changes for this functionality are somewhat
> tricky, make sure the paths are tested every boot, instead of on the
> rare occasion when we trip an INT3 while rewriting text.
> Getting the INT3 frame setup even slightly wrong will make this come
> unstuck something spectacular.
> Requested-by: Andy Lutomirski <luto@xxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
> arch/x86/kernel/alternative.c | 81 ++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 77 insertions(+), 4 deletions(-)

I'll add this to my queue, as I tested this on x86_32 and 64. I also
put in a printk("HERE in int3_magic\n") to make sure it really did get
there (although, the BUG_ON should be good enough).

The printk will be removed from the official commit. It was just for my
peace of mind.

-- Steve